Small engine maintenance is not taught anymore. I used to work for a
lawn service company who would make every lawn-mower remove and
dismantle, completely, the carburetor and gas tank from his mower,
clean it out, and reassemble it. You were given the manual and three
hours. They figured if you weren't smart enough to get it on and
running by then they could find someone else. The owner had a heart
attack and dropped dead and the kids decded this went against modern
management principles. Plenty of workers who "weren't mechanics" could
mow lawns fine, and would work cheaper, so T.J. and Wilbur-two old
hardasses we had working there for years-were replaced by Juan, Hector
and Pedro who proceeded to put them out of business promptly.
There is no feedback system and oxygen sensor-they are gravity bowl
carburetors wholly dependent on the specific gravity of the fuel, and
air absolute pressure, temperature, and humidity. Setting proper fuel
mixture is something needing to be done every time there is a drastic
change in any of the above on a B&S or Tecumseh. Never seen a Honda
close enough to know.
Hint: Learn to read spark plugs. Get the Champion magnifier and the
Second hint: Small engines are built cheap, cheap, cheap. Automobile
gas has changed and fuel system materials haven't. Unless you can find
better seals, gaskets, et al aftermarket, the stuff in car gas for EPA
will attack these. If you can find 80/87 avgas locally, it's worth the
extra buck a gallon.